ppigliucci the demarcation problem

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9 1 The Demarcation Problem A (Belated) Response to Laudan Massimo Pigliucci e Premature Obituary of the Demarcation Problem e “demarcation problem,” the issue of how to separate science from pseu- doscience, has been around since fall 1919—at least according to Karl Pop- per’s (1957) recollection of when he first started thinking about it. In Popper’s mind, the demarcation problem was intimately linked with one of the most vexing issues in philosophy of science, David Hume’s problem of induction (Vickers 2010) and, in particular, Hume’s contention that induction cannot be logically justified by appealing to the fact that “it works,” as that in itself is an inductive argument, thereby potentially plunging the philosopher straight into the abyss of a viciously circular argument. Popper famously thought he had solved both the demarcation and induc- tion problems in one fell swoop, by invoking falsification as the criterion that separates science from pseudoscience. Not only, according to Popper, do sci- entific hypotheses have to be falsifiable (while pseudoscientific ones are not), but since falsification is an application of modus tollens, and hence a type of deductive thinking, we can get rid of induction altogether as the basis for sci- entific reasoning and set Hume’s ghost to rest once and for all. As it turns out, however, although Popper did indeed have several impor- tant things to say about both demarcation and induction, philosophers are still very much debating both issues as live ones (see, e.g., Okasha 2001 on You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.

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Articulo en defensa de Popper y el demarcacionismo

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91The Demarcation ProblemA (Belated) Response to LaudanMassi moPi gli ucciTe Premature Obituary of the Demarcation ProblemTe demarcation problem, the issue of how to separate science from pseu-doscience,hasbeenaroundsincefall1919atleastaccordingtoKarlPop-pers (1957) recollection of when he frst started thinking about it. In Poppers mind,thedemarcationproblemwasintimatelylinkedwithoneofthemost vexingissuesinphilosophyofscience,DavidHumesproblemofinduction (Vickers2010)and,inparticular,Humescontentionthatinductioncannot be logically justifed by appealing to the fact that it works, as that in itself is an inductive argument, thereby potentially plunging the philosopher straight into the abyss of a viciously circular argument.Popper famously thought he had solved both the demarcation and induc-tion problems in one fell swoop, by invoking falsifcation as the criterion that separates science from pseudoscience. Not only, according to Popper, do sci-entifc hypotheses have to be falsifable (while pseudoscientifc ones are not), butsincefalsifcationisanapplicationofmodustollens,andhenceatypeof deductive thinking, we can get rid of induction altogether as the basis for sci-entifc reasoning and set Humes ghost to rest once and for all.As it turns out, however, although Popper did indeed have several impor-tantthingstosayaboutbothdemarcationandinduction,philosophersare stillverymuchdebatingbothissuesasliveones(see,e.g.,Okasha2001on You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.10Massimo Pigliucciinduction, and Hansson 2009 on demarcation). Te fact that we continue to discuss the issue of demarcation may seem peculiar, though, considering that Laudan (1983) allegedly laid to rest the problem once and for all. In a much referenced paper quite defnitively entitled Te Demise of the Demarcation Problem, Laudan concluded that the [demarcation] question is both unin-teresting and, judging by its checkered past, intractable. If we would stand up and be counted on the side of reason, we ought to drop terms like pseudo-science and unscientifc from our vocabulary (Laudan 1983, 125).At the risk of being counted on the side of unreason, in this chapter I argue that Laudans requiem for the demarcation problem was much too premature. First, I quickly review Poppers original arguments concerning demarcation andfalsifcation(butnotthoserelatingtoinduction,whichisbeyondthe scope of this contribution); second, I comment on Laudans brief history of the demarcation problem as presented in parts 2 and 4 of his paper; third, I argueagainstLaudansmetaphilosophicalinterlude(part3ofhispaper), where he sets out the demarcation problem as he understands it; and last, I proposetorethinktheproblemitself,buildingonanobservationmadeby Kuhn (1974, 803) and a suggestion contributed by Dupr (1993, 242). (Also seeinthisvolume,Boudry,chapter5;Hansson,chapter4;Koertge,chap-ter 9; and Nickles, chapter 6.) Poppers AttackPopper(1957)wantedtodistinguishscientifctheoriesorhypothesesfrom nonscientifcandpseudoscientifcones,andwasunhappywithwhathe took to be the standard answer to the question of demarcation: science, un-likepseudoscience(ormetaphysics),worksonthebasisoftheempirical method, which consists of an inductive progression from observation to theo-ries. If that were the case, Popper reckoned, astrology would have to rank as ascience,albeitasaspectacularlyunsuccessfulone(Carlson1985).Popper then set out to compare what in his mind were clear examples of good science (e.g.,AlbertEinsteinsgeneraltheoryofrelativity)andpseudoscience(e.g., Marxist theories of history, Freudian psychoanalysis, and Alfred Adlers in-dividualpsychology)tofgureoutwhatexactlydistinguishesthefrstfrom the second group. I use a much broadened version of the same comparative approachtowardtheendofthisessaytoarriveatmyownproposalforthe problem raised by Popper.Popper was positively impressed by the then recent spectacular confrma-You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem11tion of Einsteins theory afer the 1919 total solar eclipse. Photographs taken by Arthur Eddington during the eclipse confrmed a daring and precise pre-diction made by Einstein, concerning the slight degree by which light coming frombehindthesunwouldbebentbythelattersgravitationalfeld.Bythe sametoken,however,PopperwashighlyunimpressedbyMarxism,Freud-ianism, and Adlerianism. For instance, here is how he recalls his personal en-counter with Adler and his theories: Once, in 1919, I reported to [Adler] a case which to me did not seem particu-larly Adlerian, but which he found no dif culty in analysing in terms of his theory of inferiority feelings, although he had not even seen the child. Slightly shocked, I asked him how he could be so sure. Because of my thousandfold experience, he replied; whereupon I could not help saying: And with this new case, I suppose, your experience has become thousand-and-one-fold. (Popper 1957, sec. 1)RegardlessofwhetheroneagreeswithPoppersanalysisofdemarcation, thereissomethingprofoundlyrightaboutthecontrastshesetsupbetween relativity theory and psychoanalysis or Marxist history: anyone who has had even a passing acquaintance with both science and pseudoscience cannot but becompelledtorecognizethesamecleardiferencethatstruckPopperas obvious. I maintain in this essay that, as long as we agree that there is indeed a recognizable diference between, say, evolutionary biology on the one hand and creationism on the other, then we must also agree that there are demarca-tion criteriahowever elusive they may be at frst glance.Poppers analysis led him to a set of seven conclusions that summarize his take on demarcation (Popper 1957, sec. 1): 1.Teory confrmation is too easy.2.Te only exception to statement 1 is when confrmation results from risky predictions made by a theory.3.Better theories make more prohibitions (i.e., predict things that should not be observed).4.Irrefutability of a theory is a vice, not a virtue.5.Testability is the same as falsifability, and it comes in degrees.6.Confrming evidence counts only when it is the result of a serious attempt at falsifcation (this is, it should be noted, somewhat redundant with state-ment 2 above).You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.12Massimo Pigliucci7.A falsifed theory can be rescued by employing ad hoc hypotheses, but this comes at the cost of a reduced scientifc status for the theory in question.Te problems with Poppers solution are well known, and we do not need to dwell too much on them. Briefy, as even Popper acknowledged, falsifca-tionism is faced with (and, most would argue, undermined by) the daunting problem set out by Pierre Duhem (see Needham 2000). Te history of science clearly shows that scientists do not throw a theory out as soon as it appears to be falsifed by data, as long as they think the theory is promising or has been fruitful in the past and can be rescued by reasonable adjustments of ancillary conditions and hypotheses. It is what Johannes Kepler did to Nicolaus Coper-nicussearlyinsight,aswellasthereasonastronomersretainedNewtonian mechanics in the face of its apparent inability to account for the orbit of Ura-nus (a move that quickly led to the discovery of Neptune), to mention but two examples.1 Yet, as Kuhn (1974, 803) aptly noticed, even though his and Pop-perscriteriaofdemarcationdiferedprofoundly(andheobviouslythought Poppers to be mistaken), they did seem to agree on where the fault lines run between science and pseudoscience: which brings me to an examination and critique of Laudans brief survey of the history of demarcation. Laudans Brief History of DemarcationTwosectionsofLaudans(1983,secs.2,4)critiqueofdemarcationarede-votedtoabriefcriticalhistoryofthesubject,dividedintoolddemarca-tionisttraditionandnewdemarcationisttradition(andseparatedbythe metaphilosophicalinterludeinsection3,towhichIcomenext).Tough muchisrightinLaudansanalysis,Idisagreewithhisfundamentaltakeon whatthehistoryofthedemarcationproblemtellsus:forhim,therational conclusion is that philosophers have failed at the task, probably because the task itself is hopeless. For me, the same history is a nice example of how phi-losophy makes progress: by considering frst the obvious moves or solutions, then criticizing them to arrive at more sophisticated moves, which are in turn criticized, and so on. Te process is really not entirely disanalogous with that ofscience,exceptthatphilosophyproceedsinlogicalspaceratherthanby empirical evidence.Forinstance,LaudaniscorrectthatAristotlesgoalofscientifcanalysis asproceedingbylogicaldemonstrationsandarrivingatuniversalsissimply not attainable. But Laudan is too quick, I think, in rejecting Parmenides dis-You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem13tinction between episteme (knowledge) and doxa (opinion), a rejection that he traces to the success of fallibilism in epistemology during the nineteenth century(moreonthisinamoment).Butthedividinglinebetweenknowl-edgeandopiniondoesnothave(andinfactcannotbe)sharp,justlikethe dividing line between science and pseudoscience cannot be sharp, so that fal-libilism does not, in fact, undermine the possibility of separating knowledge frommereopinion.FuzzylinesandgradualdistinctionsasIarguelaterstill make for useful separations.Laudan then proceeds with rejecting Aristotles other criterion for demar-cation, the diference between know-how (typical of crafsmen) and know-why (what the scientists are aiming at), on the ground that this would make pre-Copernican astronomy a matter of crafsmanship, not science, since pre-Copernicanssimplyknewhowtocalculatethepositionsoftheplanetsand did not really have any scientifc idea of what was actually causing planetary motions. Well, I will bite the bullet here and agree that protoscience, such as pre-Copernican astronomy, does indeed share some aspects with crafsman-ship.EvenPopper(1957,sec.2)agreedthatsciencedevelopsfromproto-scientifc myths: I realized that such myths may be developed, and become testable;andthatamythmaycontainimportantanticipationsofscientifc theories.LaudanmakesmuchofGalileoGalileisandIsaacNewtonscontentions that they were not afer causes, hypothesis non fngo to use Newtons famous remarkaboutgravity,andyettheyweresurelydoingscience.Again,true enough,butbothofthosegreatthinkersstoodatthebrinkofthehistorical period where physics was transitioning from protoscience to mature science, sothatitwasclearlywaytooearlytosearchforcausalexplanations.Butno physicist worth her salt today (or, indeed, shortly afer Newton) would agree that one can be happy with a science that ignores the search for causal expla-nations.Indeed,historicaltransitionsawayfrompseudoscience,whenthey occur (think of the diference between alchemy and chemistry), involve inter-mediate stages similar to those that characterized astronomy in the sixteenth and seventeenth centuries and physics in the seventeenth and eighteenth cen-turies.ButhadastronomersandphysicistsnoteventuallyabandonedGali-leos and Newtons initial caution about hypotheses, we would have had two aborted sciences instead of the highly developed disciplines that we so admire today.Laudan then steps into what is arguably one of the most erroneous claims of his paper: the above mentioned contention that the onset of fallibilism in You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.14Massimo Pigliucciepistemology during the nineteenth century meant the end of any meaning-ful distinction between knowledge and opinion. If so, I wager that scientists themselves have not noticed. Laudan does point out that several nineteenth centuryphilosophersofsciencetriedtotakesomeofthestingoutofthis volte-face [i.e., the acknowledgment that absolute truth is not within the grasp of science] by suggesting that scientifc opinions were more probable or more reliablethannon-scientifcones(Laudan1983,115),leavinghisreadersto wonderwhyexactlysuchamovedidnotsucceed.SurelyLaudanisnotar-guingthatscientifcopinionisnotmoreprobablethanmereopinion.If hewere,weshouldcounthimamongstpostmodernepistemicrelativists,a company that I am quite sure he would eschew.Laudan proceeds to build his case against demarcation by claiming that, oncefallibilismwasaccepted,philosophersreorientedtheirfocustoinves-tigateandepistemicallyjustifyscienceasamethodratherthanasabodyof knowledge(ofcourse,thetwoaredeeplyinterconnected,butwewillleave thatasideforthepresentdiscussion).Tehistoryofthatattemptnaturally passes through John Stuart Mills and William Whewells discussions about the nature of inductive reasoning. Again, Laudan reads this history in an entirely negativefashion,whileIperhapsoutofanaturallyoptimistic tendencyseeitasyetanotherexampleofprogressinphilosophy.Mills([1843]2002) fve methods of induction and Whewells (1840) concept of inference to the best explanation represent marked improvements on Francis Bacons (1620) analysis,basedasitwaslargelyonenumerativeinduction.Tesearemile-stonesinourunderstandingofinductivereasoningandtheworkingsofsci-ence,andtodismissthemasambiguousandembarrassingisbothpre-sumptuous and a disservice to philosophy as well as to science.Laudan then moves on to twentieth-century attempts at demarcation, be-ginning with the logical positivists. It has become a fashionable sport among philosophers to dismiss logical positivism out of hand, and I am certainly not about to mount a defense of it here (or anywhere else, for that matter). But, again, it strikes me as bizarre to argue that the exploration of another corner of the logical space of possibilities for demarcationthe positivists emphasis on theories of meaningwas a waste of time. It is because the positivists and their criticsexploredandeventuallyrejectedthatpossibilitythatwehavemade further progress in understanding the problem. Tis is the general method of philosophical inquiry, and for a philosopher to use these failures as a reason to reject an entire project is akin to a scientist pointing out that because New-You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem15tonian mechanics turned out to be wrong, we have made no progress in our understanding of physics.Afer dismissing the positivists, Laudan turns his guns on Popper, another preferredtargetamongstphilosophersofscience.Here,however,Laudan comes close to admitting what a more sensible answer to the issue of demar-cation may turn out to be, one that was tentatively probed by Popper himself: One might respond to such criticisms [of falsifcationism] by saying that sci-entifc status is a matter of degree rather than kind (Laudan 1983, 121). One might indeed do so, but instead of pursuing that possibility, Laudan quickly declares it a dead end on the grounds that acute technical dif culties confront this suggestion. Tat may be the case, but it is nonetheless true that within the sciences themselves there has been quite a bit of work done (admittedly, much of it since Laudans paper) to make the notion of quantitative compari-sons of alternative theories more rigorous. Tese days this is done by way of either Bayesian reasoning (Henderson et al. 2010) or some sort of model se-lection approach like the Akaike criterion (Sakamoto and Kitagawa 1987). It is beyond me why this sort of approach could not be one way to pursue Poppers eminently sensible intuition that scientifcity is a matter of degrees. Indeed, I argue below that something along these lines is actually a much more promis-ing way to recast the demarcation problem, following an early suggestion by Dupr(1993).Fornow,though,suf ceittosaythatevenscientistswould agree that some hypotheses are more testable than others, not just when com-paring science with proto- or pseudoscience, but within established scientifc disciplinesthemselves,evenifthisjudgmentisnotexactlyquantifable.For instance, evolutionary psychologys claims are notoriously far more dif cult totestthansimilarlystructuredhypothesesfrommainstreamevolutionary biology, for the simple reason that human behavioral traits happen to be awful subjects of historical investigation (Kaplan 2002; Pigliucci and Kaplan 2006, chap. 7). Or consider the ongoing discussion about the (lack of ) testability of superstringandalliedfamilyoftheoriesinfundamentalphysics(Voit2006; Smolin 2007).Laudaneventuallygetstowhatreallyseemstobebotheringhim:Un-willingtolinkscientifcstatustoanyevidentialwarrant,twentiethcentury demarcationists have been forced into characterizing the ideologies they op-pose (whether Marxism, psychoanalysis or creationism) as untestable in prin-ciple.Veryoccasionally,thatlabelisappropriate(Laudan1983,122).Iam not sure why ideology needs to be brought in. I am certainly not naive enough You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.16Massimo Pigliuccito suggest that anyonescientists, philosophers, or pseudoscientistsdo not subscribetoideologicalpositionsthatinfuencetheirclaims.Butsurelywe canconstructivelydophilosophynonetheless,anddonothavetoconfne ourselves to politics and psychology. Popper actually wrote that the Marxist theory of history, in spite of the serious eforts of some of its founders and fol-lowers, ultimately adopted this soothsaying practice [making its predictions so vague that they become irrefutable]. In some of its earlier formulations (for example in Marxs analysis of the character of the coming social revolution) theirpredictionsweretestable,andinfactfalsifed(Popper1957,sec.2). Inotherwords,PoppersawMarxisttheoriesofhistoryasanalogoustothe modern case of cold fusion (Huizenga 1992), an initially legitimate scientifc claim that was eventually falsifed but that degenerated into a pseudoscience in the hands of a small cadre of people who simply refuse to give up the idea regardless of the evidence.AsfarasFreudianandAdleriantheoriesareconcerned,againtheyare nolongertakenseriouslyasscientifcideasbythepracticingcognitivesci-ence community, as much as they were important (particularly Freuds) in the historicaldevelopmentofthefeld(seeCiof ,thisvolume).Whenitcomes tocreationism,thingsareabitmorecomplicated:veryfewscientists,and possibly philosophers, would maintain that specifc creationist claims are not testable. Just as in the case of claims from, say, astrology or parapsychology, one can easily test young creationists contention that the earth is only a few thousand years old. But these tests do not make a science out of creationism for the simple reason that either one must accept that the contention has been conclusively falsifed, or one must resort to the inscrutable and untestable ac-tions,means,andmotivesofacreatorgod.Whenayoung-earthcreationist isfacedwithgeologicalevidenceofanoldearth,hehasseveralretortsthat seem completely logical to him, even though they actually represent the very reasons why creationism is a pseudoscience: the methods used to date rocks arefawed(forreasonsthatremainunexplained);thelawsofphysicshave changed over time (without any evidence to support the suggestion); or God simply created a world that looks like it is old so that He could test our faith (called last Tursday defense, which deserves no additional commentary). So, pace Laudan, there are perfectly good, principled, not ideological reasons tolabelMarxism,Freudianism,andcreationismaspseudoscienceseven though the details of these reasons vary from case to case.Te rest of Laudans critique boils down to the argument that no demar-cation criterion proposed so far can provide a set of necessary and suf cient You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem17conditions to defne an activity as scientifc, and that the epistemic hetero-geneity of the activities and beliefs customarily regarded as scientifc means that demarcation is a futile quest. I agree with the former point, but I argue belowthatitrepresentsaproblemonlyforatoonarrowlyconstructedde-marcationproject;thesecondpointhassometruthtoit,butitsextentand consequencesaregrosslyexaggeratedbyLaudanwithinthecontextofthis discussion. Laudans MetaphilosophyLaudanmaintainsthatthedebateaboutdemarcationhingesonthreecon-siderationsthathelabelsasmetaphilosophical(thoughitisnotclearto thisreader,atleast,whythemetaprefxisnecessary).Briefy,theseare: (1)Whatconditionsofadequacyshouldaproposeddemarcationcriterion satisfy?(2)Isthecriterionunderconsiderationoferingnecessaryorsuf -cient conditions, or both, for scientifc status? (3) What actions or judgments are implied by the claim that a certain belief or activity is scientifc or unsci-entifc? (Laudan 1983, 117). As we shall see, I agree with Laudans answer to question 1, I think that question 2 is too simplistic as formulated, and I force-fully reject his answer to question 3.Laudancorrectlyargues(question1)thatmodernphilosophersthink-ing about demarcation ought to take seriously what most people, particularly mostscientists,actuallyagreetocountasscienceandpseudoscience.Tat is, it would be futile to pursue the question in a Platonic way, attempting to arriveataprioriconclusionsregardlessofwhetherandtowhatextentthey matchscientists(andmostphilosophers)intuitionsaboutwhatscienceis and is not. Indeed, I think of the target of demarcation studies along the lines sketchedinfgure1.1:someactivities(andthetheoriesthatcharacterize them)representestablishedscience(e.g.,particlephysics,climatescience, evolutionarybiology,molecularbiology);othersareofentreatedassof sciences (e.g., economics, psychology, sociology; Pigliucci 2002), character-izedbysomeofthatepistemicheterogeneityreferredtoabove;yetmore efortsarebestthoughtofasproto-orquasi-scientifc(e.g.,theSearchfor Extra terrestrialIntelligence,superstringphysics,atleastsomeevolution-arypsychology,andscientifcapproachestohistory);fnally,anumberof activitiesunquestionablyrepresentwhatmostscientistsandphilosophers wouldregardaspseudoscience(IntelligentDesigntheory,astrology,HIV denialism,etc.).Figure1.1isobviouslyfarfromexhaustive,butitcaptures You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.18Massimo PigliucciFigure 1.1Laudansideathatnomatterhowwephilosophizeaboutitdemarcation analyses should come up with something that looks like the cluster diagram I sketched, or we would have reasonable doubts that the analysis was not on the righttrack.Tosomethismightseemlikeanundueconcessiontoempirical evidence based on common practice and intuition, and one could argue that philosophical analysis is most interesting when it does not support common sense.Tatmaybe,butourtaskhereistounderstandwhatdiferentiatesa number of actual human practices, so empirical constraints are justifed, within limits.I also agree with Laudan (1983, 118) that minimally, we expect a demarca-tion criterion to identify the epistemic or methodological features which mark of scientifc beliefs from unscientifc ones, though these criteria (necessar-ily plural, I think) would have to include much more than Laudan was likely thinking about, for instance, considerations of science as a social activity of a particular kind, with a number of structures in place (e.g., peer review) and desiderata (e.g., cultural diversity) that contribute indirectly to its epistemic and methodological features (Longino 1990).My frst major departure from Laudans metaphilosophy is with respect You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem19to his answer to question 2 above: Ideally, [a demarcation criterion] would specify a set of individually necessary and jointly suf cient conditions for de-cidingwhetheranactivityorsetofstatementsisscientifcorunscientifc (Laudan 1983, 118). He goes on to clarify that a set of necessary but not suf-fcient conditions would permit us to point to activities that are not scientifc (those lacking the necessary conditions) but could not specify which activi-tiesareindeedscientifc.Conversely,asetofsuf cient(butnotnecessary) conditions would tell us what counts as science, but not what is pseudoscien-tifc. Hence the need for necessary and suf cient conditions (though no single set of criteria needs to be both at the same time).Tis strikes me as somewhat old-fashioned, particularly for someone who has been telling his readers that many of philosophys classic pursuitssuch as a priori truths and the search for logical demonstrationswent out the win-dow with the advent of more nuanced philosophical analyses in the modern era. It seems like the search for sets of necessary and suf cient conditions to sharply circumscribe concepts that are clearly not sharp in themselves ought to give pause at least since Ludwig Wittgensteins talk of family resemblance conceptswhich inspired the above mentioned suggestion by Dupr (1993).Asiswellknown,Wittgenstein(1958)discussedthenatureofcomplex concepts that do not admit of sharp boundariesor of sets of necessary and suf cient conditionssuch as the concept of game. He suggested that the way we learn about these concepts is by example, not through logical defnitions: How should we explain to someone what a game is? I imagine that we should describe games to him, and we might add: Tis and similar things are called games. and do we know any more about it ourselves? Is it only other people whomwecannottellexactlywhatagameis?...Butthisisnotignorance. We do not know the boundaries because none have been drawn. . . . We can draw a boundary for a special purpose. Does it take that to make the concept usable? Not at all! (Ibid., 69).Figure 1.2 is my graphic rendition of Wittgensteins basic insight: games make up a family resemblance concept (also known as a cluster, in analogy to the type of diagram in fgure 1.1) that cannot be captured by a set of neces-saryandsuf cientconditions.Anysuchsetwillnecessarilyleaveoutsome activities that ought to be considered as legitimate games while letting in ac-tivitiesthatequallyclearlydonotbelongthere.ButWittgensteincorrectly argued that this is neither the result of our epistemic limitations nor of some intrinsicincoherenceintheconceptitself.Itisthewayinwhichlanguage gameswork,andphilosophyofscienceisnoexceptiontothegeneralidea You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.20Massimo PigliucciFigure 1.2ofalanguagegame.Ireturntothepossibilityofunderstandingscienceasa Wittgenstein-type cluster concept below to make it a bit more precise.I also markedly disagree with Laudan in answer to his question 3 above, where he says:Precisely because a demarcation criterion will typically assert the epistemic superiority of science over non-science, the formulation of such a criterion will result in the sorting of beliefs into such categories as sound and unsound, respectable and cranky, or reasonable and unreasonable. Philosophers should not shirk from the formulation of a demarcation criterion merely be-cause it has these judgmental implications associated with it. Quite the reverse, philosophy at its best should tell us what is reasonable to believe and what is not. But the value-loaded character of the term science (and its cognates) in our culture should make us realize that the labeling of a certain activity as scientifc or unscientifc has social and political ramifcations which go well beyond the taxonomic task of sorting beliefs into two piles. (Laudan 1983, 11920) SeemstomethatLaudanherewantstohavehiscakeandeatittoo.Tobe-gin with, the value-loaded character of science is not exactly an unqualifed You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem21social positive for all things labeled as scientifc. We regularly see large sec-tionsofthepublic,especiallyintheUnitedStates,whofatlyrejectallsorts of scientifc fndings when said public fnds them ideologically inconvenient or simply contrary to pet notions of one sort or another. Just think about the numberofAmericanswhodenytheverynotionofhuman-causedclimate changeorwhobelievethatvaccinescauseautismbothpositionsheldde-spite an overwhelming consensus to the contrary on the part of the relevant scientifccommunities.Obviously,labelingsomethingscientifcdoesnot guarantee acceptance in society at large.Moreimportant,Laudansimplycannotcoherentlyarguethatphiloso-phy at its best should tell us what is reasonable to believe and what is not and then admonish us that [the] social and political ramifcations . . . go well be-yond the taxonomic task of sorting beliefs into two piles. Of course there are political and social implications. Indeed, I would argue that if the distinction between science and pseudoscience did not have political and social implica-tions, then it would merely be an academic matter of little import outside of a small cadre of philosophers of science. Tere simply is no way, norshould there be, for the philosopher to make arguments to the rest of the world con-cerningwhatisorisnotreasonabletobelievewithoutnotjusthaving,but wanting political and social consequences. Tis is a serious game, which ought to be played seriously. Rethinking DemarcationAsBacon(1620)rightlyadmonishedus,itisnotgoodenoughtoengagein criticism(parsdestruens);onealsooughttocomeupwithpositivesugges-tions on how to move ahead (pars construens). So far I have built an argument againstLaudansprematuredeathcertifcateforthedemarcationproblem, butIhavealsohintedatthedirectionsinwhichprogresscanreasonablybe expected. I now briefy expand on those directions.TestartingpointisprovidedbyDuprs(1993)suggestiontotreatsci-ence (and therefore pseudoscience) as a Wittgensteinian family resemblance, or cluster concept, along the lines sketched in fgure 1.1. As is well knownandasillustratedfortheconceptofgameinfgure1.2familyresemblance concepts are characterized by a number of threads connecting instantiations oftheconcept,withsomethreadsmorerelevantthanotherstospecifcin-stantiations,andindeedsometimeswithindividualthreadsentirelyabsent fromindividualinstantiations.Forexample,whileacommonthreadforthe You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.22Massimo Pigliucciconcept of games is that there is a winner, this is not required in all instantia-tions of the concept (think of solitaire).Several useful concepts within science itself are best thought of as Witt-gensteinianinnature,forinstance,theideaofbiologicalspecies(Pigliucci 2003).Tedebateonhowexactlytodefnespecieshasbeengoingonfora longtimeinbiology,beginningwithAristotlesessentialismandcontinu-ingthroughErnstMayrs(1996)biologicalspeciesconcept(basedonre-productiveisolation)toanumberofphylogeneticconcepts(i.e.,basedon ancestry-descendantrelations,seeDeQueiroz1992).Teproblemcanalso beseenasonegeneratedbythesamesortofmetaphilosophyadoptedby Laudan: the search for a small set of jointly necessary and suf cient conditions adequate to determine whether a given individual belongs to a particular spe-ciesornot.Mysuggestioninthatcasefollowinguponanoriginalremark by Hull (1965) and in agreement with Templetons (1992) cohesion species conceptwasthatspeciesshouldbetreatedasclusterconcepts,withonly a few threads connecting very diferent instantiations like those represented by, say, bacterial and mammalian species, and a larger number of threads con-nectingmoresimilarlycircumscribedtypesofspecies,likevertebratesand invertebrates, for instance.Clearly, a concept like science is at least as complex as one like biological species, which means that the number of threads underlying the concept, as wellastheirrelativeimportanceforanygiveninstantiationoftheconcept, are matters for in-depth discussions that are beyond the scope of this chapter. However, I am going to provide two complementary sketches of how I see the demarcation problem, which I hope will move the discussion forward.At a very minimum, two threads run throughout any meaningful treat-ment of the diferences between science and pseudoscience, as well as of fur-therdistinctionswithinscienceitself:whatIlabeltheoreticalunderstand-ing and empirical knowledge in fgure 1.3. Presumably if there is anything we can all agree on about science, it is that science attempts to give an empiri-cally based theoretical understanding of the world, so that a scientifc theory has to have both empirical support (vertical axis in fgure 1.3) and internal co-herence and logic (horizontal axis in fgure 1.3). I am certainly not suggesting that these are the only criteria by which to evaluate the soundness of a science (orpseudoscience),butweneedtostartsomewhere.Andofcourse,both these variables in turn are likely decomposable into several factors related in complex, possibly nonlinear ways. But again, one needs to start somewhere.You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem23Figure 1.3Figure 1.3, then, represents my reconstruction of how theoretical and em-pirical strengths begin to divide the space identifed by the cluster diagram in fgure 1.1: at the upper right corner of the empirical/theoretical plane we fnd well-established sciences (and the scientifc notions that characterize them), likeparticlephysics,evolutionarybiology,andsoforth.Wecanthenmove down vertically, encountering disciplines (and notions) that are theoretically sound but have decreasing empirical content, all the way down to superstring physics,basedonaverysophisticatedmathematicaltheorythatsofarat leastmakesnocontactatallwith(new)empiricalevidence.Movingfrom the upper lef to the upper right of the diagram brings us to felds and notions thatarerichinevidence,butforwhichthetheoryisincompleteorentirely lacking, as in many of the social (sometimes referred to as sof) sciences.So far I doubt I have said anything particularly controversial about the em-pirical/theoretical plane so identifed. More interesting things happen when onemovesdiagonallyfromtheupperrighttothelowerlefcorner.Forin-stance, the proto-/quasi-science cluster in fgure 1.1 is found in the middle and middle-lower part of fgure 1.3, where theoretical sophistication is inter-mediateandempiricalcontentislow.Herebelongcontroversialdisciplines You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.24Massimo Pigliuccilikeevolutionarypsychology,theSearchforExtraterrestrialIntelligence (SETI), and scientifc approaches to the study of history. Evolutionary psy-chology is theoretically sound in the sense that it is grounded on the general theory of evolution. But as I mention above, there are serious doubts about the testability of a number of specifc claims made by evolutionary psycholo-gists (e.g., that a certain waist-to-hip ratio in human females is universally at-tractive), simply because of the peculiar dif culties represented by the human species when it comes to testing historical hypotheses about traits that do not leave a fossil record (Kaplan 2002). In the case of SETI, despite the occasional ingeniousdefenseofthatresearchprogram(CirkovicandBradbury2006), the fact remains that not only has it (so far) absolutely no empirical content, butitstheoreticalfoundationsaresketchyatbestandhavenotadvanced much since the onset of the efort in the 1960s (Kukla 2001). As for scientifc approaches to the study of history (e.g., Diamond 1999, 2011; Turchin 2003, 2007), their general applicability remains to be established, and their degree of theoretical soundness is far from being a settled matter.We fnally get to the lower lef corner of fgure 1.3, where actual pseudo-scienceresides,representedinthediagrambyastrology,IntelligentDesign (ID) creationism, and HIV denialism. While we could zoom further into this cornerandbegintomakeinterestingdistinctionsamongpseudosciences themselves (e.g., among those that pretend to be based on scientifc principles versus those that invoke completely mysterious phenomena versus those that resort to supernatural notions), they all occupy an area of the diagram that is extremely low both in terms of empirical content and when it comes to theo-reticalsophistication.Tismostcertainlydoesnotmeanthatnoempirical data bears on pseudosciences or thatat least in some casesno theoretical foundation supports them. Take the case of astrology as paradigmatic: plenty of empirical tests of astrological claims have been carried out, and the prop-erly controlled ones have all failed (e.g., Carlson 1985). Moreover, astrologers certainlycanproducetheoreticalfoundationsfortheirclaims,butthese quickly turn out to be both internally incoherent and, more damning, entirely detached from or in contradiction with very established notions from a vari-ety of other sciences (particularly physics and astronomy, but also biology). Following a Quinean conception of the web of knowledge (Quine 1951), one would then be forced to either throw out astrology (and, for similar reasons, creationism) or reject close to the entirety of the established sciences occupy-ing the upper right corner of fgure 1.3. Te choice is obvious.You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.The Demarcation Problem25Could the notions captured in fgures 1.1 and 1.3 be made a bit more pre-cise than simply invoking the Wittgensteinian notion of family resemblance? I believe this can be done in a variety of ways, one of which is to dip into the re-sources ofered by symbolic nonclassical logics like fuzzy logic (Hajek 2010). Fuzzy logic, as is well known, was developed out of fuzzy set theory to deal with situations that contain degrees of membership or degrees of truth, as in the standard problems posed by notions like being old versus young, and generally related to Sorites paradox.Fuzzy logic as a type of many-valued logic using modus ponens as its de-ductive rule is well equipped, then, to deal with the degree of scientifcity ofanotionorfeld,itselfbrokendownindegreesofempiricalsupportand theoreticalsophisticationasoutlinedabove.Forthistoactuallywork,one wouldhavetodevelopquantitativemetricsoftherelevantvariables.While suchdevelopmentiscertainlypossible,thedetailswouldhardlybeuncon-troversial.Butthisdoesnotunderminethegeneralsuggestionthatonecan make sense of science/pseudoscience as cluster concepts, which in turn can be treatedat least potentiallyin rigorous logical fashion through the aid of fuzzy logic.Here,then,iswhatIthinkarereasonableanswerstoLaudansthree metaphilosophical questions concerning demarcation: (1)What conditions of adequacy should a proposed demarcation criterion satisfy?A viable demarcation criterion should recover much (though not neces-sarily all) of the intuitive classifcation of sciences and pseudosciences generally accepted by practicing scientists and many philosophers of science, as illustrated in fgure 1.1. (2)Is the criterion under consideration ofering necessary or suf cient condi-tions, or both, for scientifc status?Demarcation should not be attempted on the basis of a small set of individually necessary and jointly suf cient conditions because sci-ence and pseudoscience are inherently Wittgensteinian family resemblance concepts (fg. 1.2). A better approach is to understand them via a multidimensional continuous classifcation based on degrees of theoretical soundness and empirical support (fg. 1.3), an approach that, in principle, can be made rigorous by the use of fuzzy logic and similar instruments. You are reading copyrighted material published by University of Chicago Press. Unauthorized posting, copying, or distributing of this work except as permitted under U.S. copyright law is illegal and injures the author and publisher.26Massimo Pigliucci(3)What actions or judgments are implied by the claim that a certain belief or activity is scientifc or unscientifc?Philosophers ought to get into the political and social fray raised by dis-cussions about the value (or lack thereof ) of both science and pseudo-science. Tis is what renders philosophy of science not just an (interest-ing) intellectual exercise, but a vital contribution to critical thinking and evaluative judgment in the broader society. Laudan (1983, 125) concluded his essay by stating that pseudo-science andunscientifcarejusthollowphraseswhichdoonlyemotiveworkfor us.Assuch,theyaremoresuitedtotherhetoricofpoliticiansandScottish sociologistsofknowledgethantothatofempiricalresearchers.Onthe contrary,thosephrasesarerichwithmeaningandconsequencesprecisely becausebothscienceandpseudoscienceplayimportantrolesinthedeal-ings of modern society. And it is high time that philosophers get their hands dirty and join the fray to make their own distinctive contributions to the all- importantsometimes even vitaldistinction between sense and nonsense. Note1. As several authors have pointed out (e.g., Needham 2000), Duhems thesis needs to be distinguished from Quines (1951), even though ofen the two are jointly known as the Duhem-Quine thesis. While Duhems adjustments to rescue a theory are local (i.e., within the circumscribed domain of the theory itself ), Quines are global, referring to changes that can be made to the entire web of knowledgeup to and including the laws of logic themselves. Accordingly, Duhems thesis properly belongs to discussions of falsifcation and demarcation, while Quines is better understood as a general critique of empiricism (in accor-dance to its appearance as an aside in his famous paper Two Dogmas of Empiricism). ReferencesBacon, Francis. 1620. Novum Organum. http://archive.org/stream/ baconsnovumorgan00bacoiala/baconsnovumorgan00bacoiala_djvu.txt.Carlson, Shawn 1985. A Double-Blind Test of Astrology. Nature 318:41925.Cirkovic, Milan M., and Robert J. Bradbury. 2006. Galactic Gradients, Postbiological Evolu-tion and the Apparent Failure of SETI. New Astronomy 11:62839.De Queiroz, Kevin 1992. Phylogenetic Defnitions and Taxonomic Philosophy. 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